v3_core: Fix variable incorrectly unbound after binary match

In the following code:

m(<<Sz:8,_:Sz/binary>>) ->
    Sz = wrong.

the Sz variable is supposed to be bound in the function header and the
matching "Sz = wrong" should cause a badarg exception.  But what
happens is that the Sz variables seems to be unbound and the matching
succeds and the m/1 function returns 'wrong'.

If the Sz variable is used directly (not matched), it will have
the expected value. Thus the following code:

m(<<Sz:8,_:Sz/binary>>) ->
    Sz.

will correctly return the value of Sz that was matched out from
the binary.

Reported-by: Bernard Duggan

1 files changed, 8 insertions, 1 deletions

diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index 1e3c670fb8..9184e14cb2 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -142,7 +142,14 @@ otp_5269(Config) when is_list(Config) ->
                          [X || <<X:X>> <- [<<1:32>>,<<2:32>>,<<3:8>>]] end,
     %% "binsize variable"          ^
                 [1,2]),
-
+    ?line check(fun() ->
+		(fun (<<A:1/binary, B:8/integer, _C:B/binary>>) ->
+			    case A of
+				B -> wrong;
+				_ -> ok
+			    end
+		 end)(<<1,2,3,4>>) end,
+		ok),
     ok.
 
 null_fields(Config) when is_list(Config) ->